1. Field of the Invention
This invention relates to an image processing apparatus and method. More particularly, the invention relates to an image processing apparatus and method for forming a visible image on a recording medium based upon an image signal that has been pulse-width modulated.
2. Description of the Related Art
The following technique is available as a method of improving the stability of image quality by adjusting the image processing characteristics of an image forming apparatus such as a copier or printer:
The method includes starting up the image forming apparatus, forming a test pattern, which has a specific grayscale pattern, on a recording medium, reading the density of the formed test pattern using an image reading device, and revising a gamma correction table based upon the image information obtained, whereby image information obtained from the test pattern is fed back to the image forming conditions.
Though the maximum density of the image obtained by revising the gamma correction table can be reduced, the fact that the maximum density capable of being produced is fixed means that the maximum density of the formed image cannot be raised. Accordingly, if the maximum density of the image formed is set high and an adjustment is made so as to lower the maximum density by a gamma correction, the desired maximum density can be obtained. However, lowering the maximum density by a gamma correction means reducing the number of tones, thereby detracting from the tonality of the image.
There is also a technique in which maximum density is changed by changing contrast potential. However, in order to change the contrast potential, it is necessary to change the output voltage of a high-voltage power supply. This involves an increase in cost. Moreover, the method of changing contrast potential does not make it possible to regulate maximum density by image resolution (number of lines).
Accordingly, an object of the present invention is to provide an image processing apparatus and method through which maximum density can be controlled without reducing the number of tones.
According to a preferred embodiment of the present invention, the foregoing object is attained by providing an image processing apparatus comprising: forming means for forming a visible image on a recording medium based upon a pulse-width modulated image signal; generating means for generating a test pattern using the forming means; and setting means for setting image forming conditions, which include at least maximum pulse width of the image signal, based upon the test pattern generated.
Another object of the present invention is to provide an image processing apparatus and method through which maximum density can be controlled in dependence upon image resolution (recording density).
According to a preferred embodiment of the present invention, the foregoing object is attained by providing an image processing apparatus comprising: forming means for forming a visible image on a recording medium based upon a pulse-width modulated image signal; generating means for generating a test pattern using the forming means; and setting means for setting image forming conditions, which include at least maximum pulse width of the image signal, based upon the test pattern generated, wherein the maximum pulse width is set for each recording density of the image.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.